WO2013098944A1 - Method and device for estimating loading state of vehicle - Google Patents

Abstract

The relationships between various predetermined loading states and the stability factor (Kh) of a vehicle and lateral acceleration (Gy) of the vehicle are stored in a storage device (30A) as reference relationships (i.e., a map). Information regarding the lateral acceleration (Gy) of the vehicle is acquired using a lateral acceleration sensor (40). Estimated values for the stability factor (Kh) of the vehicle are computed on the basis of vehicle driving data when turning. The loading state of the vehicle is estimated on the basis of whether the estimated values for the stability factor that were computed, the vehicle driving data provided for the estimated value computation, and the lateral acceleration of the vehicle of the same time are in an area of any of the reference relationships.

Description

Vehicle loading state estimation method and apparatus

The present invention relates to a method and an apparatus for estimating a loading state of a vehicle, and more particularly, a method and an estimation method for a loading state of a vehicle by using a relationship between the loading state of the vehicle and the stability factor and lateral acceleration of the vehicle. Related to the device.

A method and apparatus for estimating the loading state of a vehicle are already known. For example, in Patent Document 1 below, the relationship between the steering angle and the yaw rate with respect to the steering angular velocity is obtained in advance, the phase difference between the steering angle and the yaw rate with respect to the detected steering angular velocity, and the relationship obtained in advance. A method and apparatus for estimating the loading state of a vehicle based on it is described.

JP 2011-013023 A

[Problems to be Solved by the Invention]
The conventional loading state estimation method and apparatus described in Patent Document 1 utilizes the fact that the turning response of the vehicle to steering varies depending on the loading state of the vehicle. The phase difference between the steering angle and the yaw rate is large in a situation where the magnitude of the steering angular velocity is large, but becomes smaller as the magnitude of the steering angular velocity becomes smaller, and is substantially 0 when the magnitude of the steering angular velocity is minute. is there. Therefore, the conventional loading state estimation method and apparatus have a problem that the loading state of the vehicle cannot be estimated in a situation where the steering angular velocity is small or in a steady turning state.

A main object of the present invention is to provide an improved vehicle loading state estimation method and apparatus capable of estimating the loading state of a vehicle in a wider range of vehicle traveling conditions than before.
[Means for Solving the Problems and Effects of the Invention]

According to the present invention, the relationship among various loading states, vehicle stability factors, and vehicle lateral acceleration is obtained in advance as a reference relationship, stored in the storage means, information on the vehicle lateral acceleration is obtained, and turning The estimated value of the stability factor of the vehicle is calculated based on the traveling data of the vehicle of the vehicle, and the estimated value of the stability factor calculated and the traveling data of the vehicle used for the calculation of the estimated value A vehicle loading state estimation method is provided, wherein the vehicle loading state is estimated based on a relationship with a lateral acceleration and a reference relationship.

Further, according to the present invention, the storage means for storing the relationship among the various loading states obtained in advance, the stability factor of the vehicle, and the lateral acceleration of the vehicle as a reference relationship, and the means for acquiring the lateral acceleration information of the vehicle And a stability factor estimating means for calculating an estimated value of the stability factor of the vehicle based on the traveling data of the vehicle at the time of turning, and the estimated value of the stability factor calculated by the stability factor estimating means and the What is claimed is: 1. A vehicle loading state estimating device for estimating a loading state of a vehicle based on a relationship between a vehicle running data provided for calculation of an estimated value and a lateral acceleration of the vehicle at the same time and a reference relationship. Provided.

According to these configurations, relationships among various loading states, vehicle stability factors, and vehicle lateral acceleration are obtained in advance, and the relationships are stored in the storage means as reference relationships. Then, an estimated value of the stability factor of the vehicle is calculated based on the traveling data of the vehicle at the time of turning by the stability factor estimating means. Further, the loading state of the vehicle is estimated on the basis of the relationship between the estimated value of the stability factor, the vehicle travel data provided for the calculation of the estimated value, the lateral acceleration of the vehicle at the same time, and the reference relationship. Therefore, if the loading state of the vehicle is different from the loading state when the standard relationship is obtained, the relationship between the estimated stability factor and the lateral acceleration of the vehicle is different from the standard relationship. The vehicle loading state can be estimated based on the actual relationship to the relationship.

According to the present invention, the relationship between various loading states, vehicle stability factors, and vehicle lateral acceleration is previously obtained as a reference relationship for a plurality of vehicle weight categories and stored in the storage means. Information on the vehicle, calculate an estimate of the stability factor of the vehicle based on the running data of the vehicle at the turn, obtain information on the weight of the vehicle, and determine the vehicle weight category and the reference based on the vehicle weight. The relationship is determined, based on the calculated stability factor estimated value, the vehicle travel data provided for the calculation of the estimated value, the lateral acceleration of the vehicle at the same time, and the determined reference relationship A vehicle loading state estimation method is provided, which estimates a vehicle loading state.

Further, according to the present invention, storage means for storing, as a reference relationship, a relationship between various loading states, vehicle stability factors, and vehicle lateral acceleration, which are determined in advance for a plurality of vehicle weight categories, Means for acquiring acceleration information, stability factor estimating means for calculating an estimated value of the stability factor of the vehicle based on travel data of the vehicle at the time of turning, and means for acquiring information on the weight of the vehicle The relationship between the vehicle weight category and the reference is determined based on the vehicle weight, and the stability factor estimated value calculated by the stability factor estimating means is the same as the vehicle running data provided for the calculation of the estimated value. A vehicle loading state estimation device is provided that estimates a loading state of a vehicle based on a relationship with a lateral acceleration of the vehicle at a predetermined time and a determined reference relationship It is.

According to these configurations, the reference relationship is obtained in advance for a plurality of vehicle weight categories. Based on the weight of the vehicle, the relationship between the vehicle weight category and the reference is determined, and the loading state of the vehicle is estimated based on the relationship between the estimated stability factor and the lateral acceleration of the vehicle and the determined reference relationship. The Therefore, even when the vehicle loading state is different from the standard loading state and the vehicle weight is relatively different from the standard weight, the vehicle loading state can be reliably estimated.

Also, even if the steering angular velocity is small, even if it is a value close to 0, lateral acceleration is generated if the vehicle turns. Even if the lateral acceleration of the vehicle is a value close to 0, the stability factor of the vehicle varies depending on the loading state of the vehicle. Therefore, if the loading state of the vehicle changes, the above relationship becomes different from the reference relationship.

Therefore, according to the above four configurations, it is possible to reliably estimate the loading state of the vehicle based on the loading state of the vehicle in the case of a reference relationship even in a situation where the magnitude of the steering angular velocity is small or in a steady turning situation. Can do.

In the above configuration, it may be estimated which of the various loading states.

According to this configuration, it is possible to estimate which of the various loading states when obtaining the reference relationship.

Further, in the above configuration, an index value of deviation between the transient yaw rate of the vehicle and the actual yaw rate of the vehicle, which is in a first order lag relationship with the reference yaw rate of the vehicle, is defined as a yaw rate deviation index value, and a component below the first predetermined frequency is The stability factor of the vehicle may be estimated based on the relationship between the lateral acceleration of the removed vehicle and the yaw rate deviation index value from which the component equal to or lower than the second predetermined frequency is removed.

According to this configuration, the stability factor of the vehicle can be estimated even in a situation where the steering angular velocity is small, so that the loading state of the vehicle can be reliably ensured even in a situation where the steering angular velocity is small. Can be estimated.

Further, according to this configuration, by removing a component having a predetermined frequency or less from the detected value of the lateral acceleration of the vehicle, a stationary detection error such as an error caused by the zero point offset of the detecting means for detecting the lateral acceleration of the vehicle can be obtained. Can be removed. Similarly, by removing components below a predetermined frequency from the value for calculating the yaw rate deviation index value, stationary detection errors such as errors caused by the zero point offset of the detection means for detecting the state quantity of the vehicle are removed. be able to.

In the two-wheel model of the vehicle shown in FIG. 13, the mass and yaw moment of the vehicle are M and I, respectively, and the distances between the center of gravity 102 of the vehicle and the front and rear axles are Lf and Lr, respectively. The wheel base of the vehicle is L (= Lf + Lr). Further, the cornering forces of the front wheel 100f and the rear wheel 100r are Ff and Fr, respectively, and the cornering powers of the front wheel and the rear wheel are Kf and Kr, respectively. The actual steering angle of the front wheel 100f is δ, the slip angles of the front and rear wheels are βf and βr, respectively, and the slip angle of the vehicle body is β. Further, the lateral acceleration of the vehicle is Gy, the vehicle yaw rate is γ, the vehicle speed is V, and the vehicle yaw angular velocity (differential value of the yaw rate γ) is γd. The following formulas 1 to 6 are established depending on the balance of the force and moment of the vehicle.

MGy = Ff + Fr (1)
Iγd = LfFf−LrFr (2)
Ff = -Kfβf (3)
Fr = -Krβr (4)
βf = β + (Lf / V) γ−δ (5)
βr = β- (Lr / V) γ (6)

From the above formulas 1 to 6, the following formula 7 is established.

Assuming that the vehicle speed V is substantially constant, the Laplace operator is converted to Laplace with the Laplace operator as s, and the yaw rate γ is arranged, so that the following Equations 8 to 10 are established. A normative yaw rate γ (s) is required.

Kh in the above equation 9 is a stability factor, and Tp in the above equation 10 is a coefficient relating to the vehicle speed V of the first-order lag system having a time constant depending on the vehicle speed, that is, the “steering response time constant coefficient” in this specification. It is a coefficient to call. These values are parameters that characterize the steering response related to the yaw motion of the vehicle, and indicate the turning characteristics of the vehicle. The above equation 8 is an equation for calculating the yaw rate γ of the vehicle from the actual steering angle δ of the front wheels, the vehicle speed V, and the lateral acceleration Gy. Assuming that the yaw rate calculated from this linearized model is the transient yaw rate γtr, the transient yaw rate γtr is a value of a first-order lag with respect to the steady standard yaw rate γt expressed by the following equation 11.

Therefore, in the above configuration, the transient yaw rate γtr may be calculated according to the following equation 12 corresponding to the above equation 8.

The deviation Δγt between the steady normative yaw rate γt and the detected yaw rate γ during steady turning of the vehicle is expressed by the following equation 13 where the design value and true value of the stability factor are Khde and Khre, respectively.

When the yaw rate deviation Δγt is converted into the steering wheel deviation Δδt by multiplying both sides of the above expression 13 by L / V, the steering wheel deviation Δδt of the front wheel is expressed by the following expression 14. This deviation Δδt of the steering angle of the front wheels is one of index values of deviation between the steady standard yaw rate γt and the detected yaw rate γ, and does not depend on the vehicle speed.
Δδt = (Khre−Khde) GyL (14)

Therefore, the deviation Δδt of the steering angle of the front wheels can be calculated according to the equation 14 as an index value of the deviation between the steady standard yaw rate and the actual yaw rate γ.

From Equation 14, the relationship between the lateral acceleration Gy and the front wheel rudder angle deviation Δδt, in other words, the gradient (Khre-Khde) L of the relationship between the lateral acceleration Gy and the front wheel rudder angle deviation Δδt in the orthogonal coordinate system. It can be understood that the stability factor estimated value Khp can be obtained according to the following equation 15 by obtaining the value by least square method or the like.
Khp = Khde + gradient / L (15)

Also, if the sensor zero point offset errors for the vehicle yaw rate γ, lateral acceleration Gy, and front wheel steering angle δ are γ0, Gy0, and δ0, respectively, the detected values of the vehicle yaw rate, lateral acceleration, and front wheel steering angle are γ + γ0, Gy + Gy0 and δ + δ0. Therefore, the deviation Δγt between the steady reference yaw rate γt and the detected yaw rate at the time of steady turning of the vehicle is expressed by the following equation (16).

When the yaw rate deviation Δγt is converted into the steering wheel deviation Δδt by multiplying both sides of the above equation 16 by L / V, the steering wheel deviation Δδt of the front wheel is expressed by the following equation 17. The relationship between the lateral acceleration Gy of the vehicle and the deviation Δδt of the rudder angle of the front wheels expressed by the following equation 17 is as shown in FIG.

Δ0−KhdeGy0L in the above equation 17 is a constant, but γ0L / V changes according to the vehicle speed V. Therefore, the intercept of the vertical axis of the graph shown in FIG. Therefore, when the detected value of the yaw rate γ of the vehicle includes an error of the sensor zero offset, the relationship of the deviation Δδt of the steering angle of the front wheels to the lateral acceleration Gy changes depending on the vehicle speed, so the stability factor is accurately set. Cannot be estimated.

Also, in order to increase the accuracy of stability factor estimation, measures such as estimating the stability factor for each vehicle speed are required. Therefore, there is a problem that the data such as the yaw rate γ necessary for the stability factor estimation becomes enormous, the calculation load of the turning characteristic estimation device becomes excessive, and it takes a long time to estimate the stability factor.

Here, the lateral acceleration of the vehicle from which the component below the first predetermined frequency is removed is Gyft, and the deviation of the steering angle of the front wheel from which the component below the second predetermined frequency is removed is Δδtft. If the first and second predetermined frequencies are sufficiently higher than the change speed of γ0 L / V accompanying the change in the vehicle speed V, the error Gy0 is not included in Gyft, and the errors γ0, δ0 are also included in Δδtft. The error due to is not included. Therefore, the following expression 18 corresponding to the above expression 14 is established. The relationship between the lateral acceleration Gyft of the vehicle expressed by the following equation 18 and the deviation Δδtft of the steering angle of the front wheels is as shown in FIG. 15, and the straight line of equation 18 passes through the origin regardless of the vehicle speed V.
Δδtft = (Khre−Khde) GyftL (18)

Therefore, the relationship of the deviation Δδtft of the front wheel steering angle to the lateral acceleration Gyft, in other words, the gradient (Khre−Khde) L of the relationship between the lateral acceleration Gyft and the deviation Δδtft of the front wheel steering angle in the orthogonal coordinate system is obtained. By determining the estimated value Khp of the stability factor according to the above equation 15, the estimated value Khp of the stability factor can be determined without being affected by the error of the zero offset of the sensor.

Therefore, in the above configuration, the estimated value of the stability factor may be calculated according to the above equation 15 using the ratio of the steering angle deviation Δδtft of the front wheels to the lateral acceleration Gyft as a gradient.

16 to 18 are graphs showing the time series waveform X, the time series waveform Y, and the Lissajous waveform of X and Y. 16 shows a case where there is no phase difference between the two time series waveforms X and Y, FIG. 17 shows a case where the phase of the time series waveform Y is delayed from the phase of the time series waveform X, and FIG. The case where the phase of the series waveform Y is ahead of the phase of the time series waveform X is shown. In particular, in FIGS. 17 and 18, a thick one-dot chain line indicates a Lissajous waveform of the integrated value of X and the integrated value of Y.

From FIG. 16 to FIG. 18, according to the ratio of the integrated value of Y to the integrated value of X, even when there is a phase difference between the two time series waveforms X and Y, the influence is reduced to obtain the ratio Y / X. I understand that I can do it.

Therefore, in the above configuration, the estimated value of the stability factor may be calculated according to the above equation 15 using the ratio of the integrated value Δδtfta of the steering angle deviation Δδtft of the front wheels to the integrated value Gyfta of the lateral acceleration Gyft as a gradient.

In the above description, the case of steady turning of the vehicle has been described. However, in the case of transient turning of the vehicle, first-order lag filter processing is performed on the steering wheel deviation Δδtft and its integrated value Δδtfta, and the lateral acceleration Gyft A first-order lag filtering process is performed on the integrated value Gyfta. In this case, by making the time constant of the first-order lag filtering process the same, the gradient is calculated in the same manner as in the case of steady turning of the vehicle based on the value after the first-order lag filtering process, Can be calculated.

In the above configuration, the vehicle is an automobile, and various loading states are the standard state for two passengers, the front loading state where the front loading amount is larger than the standard state, and the rear loading amount larger than the standard state Side loading conditions may be included.

Further, in the above configuration, the dead zone threshold of the vehicle travel control may be changed according to the estimated loading state of the vehicle.

In the above-described configuration, the vehicle weight information may be estimated based on the relationship between the acceleration / deceleration operation amount of the driver and the vehicle acceleration / deceleration.

In the above configuration, the means for acquiring the vehicle lateral acceleration information may detect the vehicle lateral acceleration.

In the above configuration, the means for acquiring the vehicle lateral acceleration information may acquire the vehicle lateral acceleration information as the product of the vehicle yaw rate and the vehicle speed.

Further, in the above configuration, the vehicle sta- tus is determined based on the relationship between the lateral acceleration of the vehicle from which the component below the first predetermined frequency is removed and the yaw rate deviation index value from which the component below the second predetermined frequency is removed. The ability factor may be estimated.

Further, in the above configuration, the component below the first predetermined frequency may be removed from the lateral acceleration of the vehicle by the high-pass filter processing, and the component below the second predetermined frequency may be removed from the yaw rate deviation index value by the high-pass filter processing. .

In the above configuration, the first and second predetermined frequencies may be the same frequency.

In the above configuration, the vehicle speed is set to V, the vehicle wheelbase is set to L, and the deviation between the vehicle's transient yaw rate and the vehicle's actual yaw rate is multiplied by L / V. A value obtained by converting the deviation from the actual yaw rate into the deviation of the steering angle of the front wheels may be calculated.

1 is a schematic configuration diagram showing a first embodiment of a vehicle loading state estimation method and apparatus according to the present invention. It is a flowchart which shows the loading condition estimation routine in 1st embodiment. It is a flowchart which shows the estimation calculation routine of the stability factor Kh in 1st embodiment. 6 is a flowchart showing a loading state estimation routine in a second embodiment of a vehicle loading state estimation method and apparatus according to the present invention. It is a graph which shows the relationship of the reference | standard for the relationship between the various loading states calculated | required previously, the stability factor Kh of a vehicle, and the lateral acceleration Gy of a vehicle. It is a graph which shows the reference | standard relationship about the relationship between the various loading states calculated | required previously about the small weight classification of the vehicle, the stability factor Kh of a vehicle, and the lateral acceleration Gy of a vehicle. It is a graph which shows the relationship of the reference | standard for the various loading states previously calculated | required about the heavy weight classification | category of the vehicle, the relationship between the vehicle stability factor Kh, and the vehicle lateral acceleration Gy. It is a flowchart which shows the principal part of the estimation calculation routine of the stability factor Kh in a 1st modification. It is a graph which shows the relationship between the steering frequency fs and the cutoff frequency fhc of a high-pass filter process. It is a flowchart which shows the principal part of the estimation calculation routine of the stability factor Kh in a 2nd modification. It is a graph which shows the relationship between the steering frequency fs, the cutoff frequency fhc of a high-pass filter process, and the absolute value of the longitudinal acceleration Gx of a vehicle. It is a flowchart which shows the principal part of the estimation calculation routine of the stability factor Kh in a 3rd modification. It is explanatory drawing which shows the two-wheel model of the vehicle for estimating a stability factor. It is a graph which shows the relationship between lateral acceleration Gy of a vehicle, and deviation (delta) t of the steering angle of a front wheel. It is a graph which shows the relationship between lateral acceleration Gyft of the vehicle from which the component below the 1st predetermined frequency was removed, and deviation (delta) tft of the steering angle of the front wheel from which the component below the 2nd predetermined frequency was removed. It is a graph which shows the Lissajous waveform of two time series waveforms X and Y, and X and Y about the case where there is no phase difference in two time series waveforms X and Y. 7 is a graph showing two time series waveforms X, Y and a Lissajous waveform of X and Y when the phase of the time series waveform Y is delayed from the phase of the time series waveform X. 6 is a graph showing two time-series waveforms X, Y, and a Lissajous waveform of X and Y when the phase of the time-series waveform Y is ahead of the phase of the time-series waveform X.

The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.
[First embodiment]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle loading state estimation method and apparatus according to the present invention.

In FIG. 1, reference numeral 50 denotes an overall loading state estimation device for the vehicle 10. The vehicle 10 has left and right front wheels 12FL and 12FR and left and right rear wheels 12RL and 12RR. The left and right front wheels 12FL and 12FR, which are steered wheels, are steered via tie rods 18L and 18R by a rack and pinion type power steering device 16 that is driven in response to steering of the steering wheel 14 by the driver.

The braking force of each wheel is controlled by controlling the braking pressure of the wheel cylinders 24FR, 24FL, 24RR, 24RL by the hydraulic circuit 22 of the braking device 20. Although not shown in the drawing, the hydraulic circuit 22 includes an oil reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven according to the depression operation of the brake pedal 26 by the driver. It is controlled by the master cylinder 28 and, if necessary, is controlled by the electronic control unit 30 as described later.

The master cylinder 28 is provided with a pressure sensor 32 for detecting the master cylinder pressure Pm, that is, the pressure in the master cylinder, and the steering column connected with the steering wheel 14 is provided with a steering angle sensor 34 for detecting the steering angle θ. ing. A signal indicating the master cylinder pressure Pm detected by the pressure sensor 32 and a signal indicating the steering angle θ detected by the steering angle sensor 34 are input to the electronic control unit 30.

The vehicle 10 includes a yaw rate sensor 36 for detecting the actual yaw rate γ of the vehicle, a longitudinal acceleration sensor 38 for detecting the longitudinal acceleration Gx of the vehicle, a lateral acceleration sensor 40 for detecting the lateral acceleration Gy of the vehicle, and a vehicle speed for detecting the vehicle speed V. 42 is provided. A signal indicating the actual yaw rate γ detected by the yaw rate sensor 36 is also input to the electronic control unit 30. The steering angle sensor 34, the yaw rate sensor 36, and the lateral acceleration sensor 40 detect the steering angle, the actual yaw rate, and the lateral acceleration, respectively, with the left turning direction of the vehicle being positive.

Although not shown in detail in the figure, the electronic control unit 30 includes, for example, a CPU, a ROM 30A, an EEPROM, a RAM, a buffer memory, and an input / output port device, which are connected to each other by a bidirectional common bus. Includes a microcomputer with a general configuration. The EEPROM stores an estimated value of the stability factor Kh and the like. The estimated value of the stability factor Kh and the like are appropriately calculated by being calculated based on the running data of the vehicle when the vehicle is in a turning state, as will be described in detail later. Updated.

ROM 30A stores a stability factor Kh used for calculation of the standard yaw rate γt and default values Kh00 and Tp00 of the steering response time constant coefficient Tp. These default values are set for each vehicle when the vehicle is shipped. Further, as shown in FIG. 5, the ROM 30A functions as a storage unit that stores a relationship between various previously obtained loading conditions, stability factor Kh, and absolute value of the lateral acceleration Gy of the vehicle as a map.

As shown in FIG. 1, a signal indicating the accelerator opening Acc is input to the engine control device 44 from an accelerator opening sensor 48 provided on the accelerator pedal 46. The engine control device 44 controls the output of the engine (not shown) based on the accelerator opening degree Acc, and exchanges signals with the electronic control device 30 as necessary. The engine control device 44 may also be constituted by a single microcomputer including a CPU, a ROM, a RAM, an input / output port device and a drive circuit, for example.

The electronic control unit 30 estimates the loading state of the vehicle according to the flowchart shown in FIG. In particular, in the first embodiment, the electronic control unit 30 calculates the estimated value of the stability factor Kh of the vehicle, and shows the estimated value of the stability factor Kh and the absolute value of the lateral acceleration Gy of the vehicle in FIG. The loading state of the vehicle is estimated based on the displayed map. When the electronic control unit 30 determines that the vehicle is in a loading state higher than the standard state for two-seater riding, the control start threshold of the vehicle running control such as the vehicle rollover suppression control is set to a value for the high loading state. Correct it.

Particularly, when the vehicle starts turning according to the flowchart shown in FIG. 3, the electronic control unit 30 calculates a steady-state standard yaw rate γt based on turning traveling data such as a steering angle. The electronic control unit 30 calculates a primary yaw transient yaw rate γtr by performing a first-order lag filter operation using the steering response time constant coefficient Tp with respect to the steady standard yaw rate γt. Further, the electronic control unit 30 calculates a front wheel rudder angle deviation converted value Δδ of the yaw rate deviation in which the deviation between the transient yaw rate γtr and the actual yaw rate γ of the vehicle is replaced with the deviation of the rudder angle of the front wheels.

Further, the electronic control unit 30 calculates the lateral acceleration Gyft of the vehicle after the first-order lag filtering process by performing a first-order lag filter operation on the lateral acceleration Gy of the vehicle by the steering response time constant coefficient Tp. The electronic control unit 30 then calculates the vehicle lateral acceleration Gyftbpf and yaw rate deviation front wheel steering angle deviation converted value Δδbpf after the bandpass filter processing based on the vehicle lateral acceleration Gyft and the yaw rate deviation front wheel steering angle deviation converted value Δδ. To do.

The electronic control unit 30 calculates the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle, and calculates the ratio Δδa / ΔGya of the integrated values. Further, the electronic control unit 30 calculates the estimated value of the stability factor Kh as the sum of the initial value of the stability factor Kh used for the calculation of the steady-state normative yaw rate γt and the correction amount based on the ratio Δδa / ΔGya of the integrated values. To do. The electronic control unit 30 stores the estimated value of the stability factor Kh and the lateral acceleration Gy of the vehicle used for the calculation in the EEPROM when a preset condition is satisfied.

Next, the vehicle loading state estimation routine in the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals. The same applies to the second embodiment described later.

First, control is started from step 10, and in step 20, a signal indicating the vehicle lateral acceleration Gy detected by each sensor is read.

In step 30, it is determined whether or not a preset loading condition estimation permission condition is satisfied. When a negative determination is made, the control returns to step 20, and when an affirmative determination is made, the control proceeds to step 60. In this case, for example, when the vehicle speed V is equal to or higher than the reference value, the vehicle is not in an acceleration / deceleration state, and no wheel slip occurs, it may be determined that the permission condition for loading state estimation is satisfied.

In step 60, it is determined in which region of the map the odd combination of the estimated stability factor Kh and the lateral acceleration Gy of the vehicle stored in the EEPROM belongs to the graph shown in FIG. By doing so, the loading state of the vehicle is estimated. In this case, when a combination belongs to a plurality of areas, it may be estimated to a loading state with a larger number of combinations.

In step 70, it is determined whether the vehicle is in a loaded state based on the estimation result in step 60. When the vehicle is in the loaded state, the loaded state is the rear stack (the center of gravity is behind the standard position), the center stack (the center of gravity is substantially the same as the standard position), the front stack (the center of gravity It is also determined whether the position is a position closer to the front than the position in the standard state. When a negative determination is made, that is, when it is determined that the vehicle is in a non-loading state, the control returns to step 20, and when an affirmative determination is made, the control proceeds to step 80.

In step 80, the threshold value of the vehicle traveling control is corrected according to whether the estimated loading state of the vehicle is a post-loading state, a center-loading state, or a pre-loading state. In this case, the constants and coefficients of the equation for calculating the control amount of the travel control may be modified according to which of the loading states.

Next, the routine for estimating the stability factor Kh in the first embodiment will be described with reference to the flowchart shown in FIG.

In step 120, a signal indicating the steering angle .theta. Detected by each sensor is read. In step 130, high frequency noise is removed from the steering angle .theta. Read in step 120. Therefore, a low-pass filter process is performed.

In step 140, the vehicle speed V is calculated based on the wheel speed Vwi, the steering angle δ of the front wheels is calculated based on the steering angle θ, and the steady standard yaw rate γt is calculated according to the above equation 11.

In step 150, the steering response time constant coefficient Tp is set to a default value Tp00 that is preset at the time of shipment of the vehicle. When the steering response time constant coefficient Tp is estimated based on the travel data of the vehicle, the steering response time constant coefficient Tp may be set to the estimated value.

In step 160, a first-order lag filter calculation is performed using the steering response time constant coefficient Tp in accordance with the above equation 12, whereby a transient yaw rate γtr based on the reference yaw rate γt calculated in step 140 is calculated.

In step 170, the first-order lag filter operation is performed on the lateral acceleration Gy of the vehicle by the steering response time constant coefficient Tp according to the following equation 19, thereby calculating the lateral acceleration Gyft of the vehicle after the first-order lag filter processing. Is done.

In step 180, the front wheel rudder angle deviation converted value Δδ of the yaw rate deviation in which the deviation between the transient yaw rate γtr and the actual yaw rate γ is replaced with the deviation of the front wheel rudder angle is calculated according to the following equation 20.

In step 190, the zero point of the sensor is calculated with respect to the lateral acceleration Gyft of the vehicle after the first-order lag filtering process calculated in step 170 and the front wheel steering angle deviation converted value Δδ of the yaw rate deviation calculated in step 180. A high-pass filter process for removing the influence of the offset is performed. The high-pass filter process in this case may be a primary high-pass filter process in which a value smaller than the cut-off frequency of the low-pass filter process in step 130 is set as the cut-off frequency.

As described above, since the low pass filter process is performed in step 130, the front wheel steering angle deviation converted value Δδ of the lateral acceleration Gyft and yaw rate deviation of the vehicle after the first-order lag filter process is performed by performing the high pass filter process. The same result as that obtained when the band pass filter processing is performed is obtained. Therefore, the front wheel steering angle deviation converted value Δδ of the lateral acceleration Gyft and yaw rate deviation of the vehicle subjected to the high-pass filter processing in step 190 is converted into the front wheel steering angle deviation converted value of the vehicle lateral acceleration Gyftbpf and yaw rate deviation after the band pass filter processing, respectively. Expressed as Δδbpf.

In step 200, it is determined whether or not the vehicle is in a turning state. If a negative determination is made, the control returns to step 120. If an affirmative determination is made, the control proceeds to step 210. In this case, whether or not the vehicle is turning is determined whether or not the absolute value of the lateral acceleration Gy of the vehicle is greater than or equal to the reference value in a situation where the vehicle is traveling at a vehicle speed greater than or equal to the reference value. The determination is made by determining whether the absolute value of the actual yaw rate γ of the vehicle is greater than or equal to a reference value and whether the absolute value of the product of the yaw rate γ of the vehicle and the vehicle speed V is greater than or equal to the reference value. Good.

In step 210, the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation after the current bandpass filter processing calculated in step 230 of the previous cycle and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are obtained. A determination is made as to whether adjustment is necessary. When a negative determination is made, control proceeds to step 230, and when an affirmative determination is made, control proceeds to step 220.

In this case, when the following (A1) or (A2) is established, it may be determined that the integrated values Δδa and ΔGya need to be adjusted. (A2) is a determination condition when the steering response time constant coefficient Tp is estimated and the steering response time constant coefficient Tp is set to the estimated value in step 50.
(A1) The absolute value of the deviation ΔKh between the stability factor Kh when the integrated values Δδa and ΔGya were adjusted last time and the current stability factor Kh estimated in step 250 of the previous cycle is the stability factor. The standard value for deviation is exceeded.
(A2) The absolute value of the deviation ΔTp between the steering response time constant coefficient Tp when the integrated values Δδa and ΔGya were adjusted last time and the current steering response time constant coefficient Tp set in step 150 of the current cycle is The reference value for deviation of the steering response time constant coefficient is exceeded.

In step 220, a preset lower limit value of the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation after the bandpass filter processing is set to Δδamin (positive constant), and the vehicle after the bandpass filter processing is processed. The adjustment gain Gaj is calculated according to the following equation 21 with the preset lower limit value of the integrated value ΔGya of the lateral acceleration Gyftbpf as ΔGyamin (positive constant). In the following equation 21, MIN means that the minimum value in the parentheses is selected, and MAX means that the maximum value in the parentheses is selected. This is the same for other similar equations.

In step 220, an integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the adjusted yaw rate deviation and an integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are calculated according to the following equations 22 and 23.
Δδa = current Δδa × Gaj (22)
ΔGya = Current ΔGya × Gaj (23)

In step 230, when the lateral acceleration Gyftbpf of the vehicle is a positive value, the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are respectively expressed by the following equations 24 and 24: 25 is calculated.
Δδa = current Δδa + Δδbpf (24)
ΔGya = Current ΔGya + Gyftbpf (25)

When the lateral acceleration Gyftbpf of the vehicle is not a positive value, the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are calculated according to the following equations 26 and 27, respectively. .
Δδa = current Δδa−Δδbpf (26)
ΔGya = Current ΔGya−Gyftbpf (27)

In step 240, the integrated value ratio Δδa / ΔGya is calculated by dividing the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation by the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle.

In step 250, the estimated value of the stability factor Kh is calculated according to the following equation 28 in which the stability factor design value Khde in the equation 15 is set to the initial value Kh0 of the stability factor.
Kh = Kh0 + (Δδa / ΔGya) / L (28)

In step 260, it is determined whether or not it is permitted to store the estimated value of the stability factor Kh in the EEPROM by determining whether or not a preset permission condition is satisfied. . When a negative determination is made, the control returns to step 120. When an affirmative determination is made, in step 270, the estimated value of the stability factor Kh is stored in the EEPROM, and thereby the stability factor stored in the EEPROM. The estimated value of Kh is updated. Further, the lateral acceleration Gy of the vehicle used for the calculation is stored in the EEPROM together with the estimated value of the stability factor Kh for each preset cycle.

In the operation of the first embodiment configured as described above, if it is determined in step 30 that the condition for permitting the loading state estimation is satisfied, the stability factor Kh is determined in step 60. The loading state of the vehicle is estimated based on the estimated value and the lateral acceleration Gy of the vehicle.

Therefore, when the loading state of the vehicle changes from the standard state, the relationship between the vehicle stability factor Kh and the lateral acceleration Gy can be used to reliably estimate the loading state of the vehicle.

Further, according to the first embodiment, the stability factor Kh of the vehicle is estimated, and the lateral acceleration Gy of the vehicle at the same time as the traveling data of the vehicle provided for the estimation is calculated together with the estimated value of the stability factor Kh. Just remember. Accordingly, it is possible to easily estimate the loading state of the vehicle as compared with the case of the second embodiment described later in which the weight W of the vehicle is estimated.

Further, according to the first embodiment, the threshold value of the vehicle traveling control is determined depending on whether the estimated loading state of the vehicle is a post-loading state, a center-loading state, or a pre-loading state. Will be corrected. Therefore, it is possible to appropriately control the start timing of the vehicle traveling control in accordance with the loading state of the vehicle as compared with the case where the loading state of the vehicle is not estimated.
[Second Embodiment]

FIG. 4 is a flowchart showing a loading state estimation routine in the second embodiment of the vehicle loading state estimation method and apparatus according to the present invention. In FIG. 4, the same steps as those shown in FIG. 2 are assigned the same step numbers as those shown in FIG.

In the second embodiment, when an affirmative determination is made in step 30, the weight W of the vehicle is estimated in step 40, and the value is stored in the EEPROM. Since the weight of the vehicle does not change during the traveling of the vehicle, this step may be skipped when the weight W of the vehicle has already been estimated after the start of traveling.

In this case, the weight W of the vehicle may be estimated as follows. First, the longitudinal acceleration of the vehicle based on the driver's braking / driving is estimated. That is, the estimated longitudinal acceleration Gxh of the vehicle is calculated based on the master cylinder pressure Pm indicating the amount of braking operation of the driver during braking, and the estimated longitudinal acceleration of the vehicle based on the accelerator opening Acc indicating the amount of driving operation of the driver during driving. Gxh is calculated. Then, based on the deviation between the estimated longitudinal acceleration Gxh and the longitudinal acceleration Gx detected by the longitudinal acceleration sensor 38, the weight W of the vehicle is estimated.

In step 50, the weight W of the vehicle estimated in step 40 is the value of the small weight section that is equal to or smaller than the reference value W0 (positive constant) or the value of the large weight section that is larger than the reference value W0. Is decided. Further, when the vehicle weight W is the value of the small weight class, the loading state estimation map is determined to be the map for the small weight class shown in FIG. 6, and when the vehicle weight W is the value of the large weight class. The map for estimating the loading state is determined to be the map for heavy weight classification shown in FIG. Note that the number of weight categories and maps of the vehicle may be three or more.

In step 60, the loading state of the vehicle is estimated in the same manner as in step 60 of the first embodiment using the map determined in step 50, and then the first embodiment. Step 70 is executed in the same manner as in.

In step 80, the vehicle running control threshold is corrected in accordance with whether the vehicle loading state is a rear loading state, a central loading state, or a previous loading state, and the vehicle weight W. The In this case, the constants and coefficients of the equation for calculating the control amount of the travel control may be modified according to the loaded state and the weight W of the vehicle.

Thus, according to the second embodiment, as in the case of the first embodiment described above, when the vehicle loading state changes from the standard state, the relationship between the vehicle stability factor Kh and the lateral acceleration Gy also changes. This makes it possible to reliably estimate the loading state of the vehicle.

Further, according to the second embodiment, the weight W of the vehicle is estimated, and a map for estimating the loading state is determined based on the weight W of the vehicle. Therefore, the loading state of the vehicle can be properly estimated even in the case of a vehicle in which the loading load such as the number of passengers in the vehicle and the loaded luggage fluctuates relatively large.

In addition, according to the second embodiment, the estimated loading state of the vehicle is a post-loading state, a center-loading state, a pre-loading state, and the weight W of the vehicle. The threshold value for the travel control is corrected. Accordingly, it is possible to appropriately control the start timing of the vehicle travel control in accordance with the vehicle weight as compared with the case where the vehicle weight is not taken into consideration.

In particular, according to the first and second embodiments, the estimated value of the stability factor Kh is calculated according to the routine shown in FIG. 3, so even when the steering angular velocity is small or in a steady turning situation. The stability factor Kh of the vehicle can be estimated. Therefore, it is possible to reliably estimate the loading state of the vehicle even when the steering angular velocity is small or in a steady turning situation.

In the operation of the first and second embodiments configured as described above, the estimated value of the stability factor Kh is calculated according to the flowchart shown in FIG.

That is, in step 140, the steady standard yaw rate γt is calculated, and in step 160, the transient yaw rate γtr is calculated based on the steady standard yaw rate γt. Further, in step 170, the lateral acceleration Gyft of the vehicle after the first-order lag filtering is calculated, and in step 180, the deviation between the transient yaw rate γtr and the actual yaw rate γ is replaced with the deviation of the steering angle of the front wheels. The front wheel rudder angle deviation converted value Δδ is calculated.

In step 190, the high-pass filter processing is performed on the vehicle lateral acceleration Gyft and the front wheel rudder angle deviation converted value Δδ of the yaw rate deviation, thereby calculating the actual yaw rate γbpf after the band-pass filter processing. The front wheel rudder angle of the yaw rate deviation index value after the band pass filter processing is obtained as a value obtained by replacing the magnitude of the deviation between the actual yaw rate γbpf after the band pass filter processing and the transient yaw rate γ trbpf with the magnitude of the steering wheel deviation of the front wheels. A deviation converted value Δδbpf is calculated.

In step 230, the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are calculated. Also, in step 240, the integrated value ratio Δδa / ΔGya is calculated by dividing the integrated value Δδa of the yaw rate deviation converted into the front wheel steering angle deviation Δδbpf by the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle.

Further, in step 250, the estimated value of the stability factor Kh is obtained as the sum of the initial value Kh0 of the stability factor Kh used for the calculation of the steady-state standard yaw rate γt and the correction amount based on the ratio Δδa / ΔGya of the integrated values. Calculated.

Thus, according to each of the above-described embodiments, the initial value of the stability factor used for the calculation of the steady-state standard yaw rate γt of the vehicle is set so that the transient yaw rate γtr of the vehicle approaches the true yaw rate. The estimated value of the stability factor Kh can be calculated as a value corrected on the basis of the relationship. Therefore, the estimated value of the stability factor is corrected so that the estimated value of the stability factor approaches the true stability factor, and thereby the estimated value of the stability factor can be obtained as a value close to the true stability factor.

In particular, according to each of the above-described embodiments, the steady-state normative yaw rate γt is calculated based on the steering angle θ and the like subjected to the low-pass filter processing in step 130. In step 190, the vehicle's lateral acceleration Gyft and yaw rate deviation front wheel rudder angle deviation converted value Δδ are subjected to high-pass filter processing, so that the vehicle's lateral acceleration Gyftbpf and yaw rate deviation front wheel rudder after band pass filter processing are performed. An angular deviation converted value Δδbpf is calculated. Further, in step 230, an integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and an integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are calculated, and in step 240, a ratio Δδa / ΔGya of the integrated values is calculated as a ratio therebetween. Is calculated.

Therefore, not only the high-frequency noise included in the detected steering angle θ etc. can be removed, but also the influence of the zero point offset of the yaw rate sensor 36 etc. can be eliminated. Therefore, it is possible to calculate the lateral acceleration Gyftbpf of the vehicle and the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation by eliminating the influence of the zero offset of the sensor, so that the stability factor is compared with the case where the high-pass filter processing is not performed. Kh can be estimated accurately. In addition, the number of high-pass filter processes can be reduced as compared with the case where the high-pass filter process is performed on the steering angle θ, the lateral acceleration Gy, and the actual yaw rate γ used for the calculation of the steady-state standard yaw rate γt. The calculation load of the electronic control unit 30 can be reduced.

It should be noted that bandpass filter processing may be performed on the front wheel steering angle deviation converted value Δδ of the vehicle lateral acceleration Gy and yaw rate deviation without performing lowpass filter processing on the steering angle θ or the like. In this case, the stability factor Kh can be accurately estimated while effectively removing high-frequency noise, and the number of operations required for the filter processing can be reduced as compared with the above-described embodiments. As a result, the calculation load of the electronic control unit 30 can be reduced.

Further, according to each of the embodiments described above, the steady state reference yaw rate γt is calculated based on the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle after the bandpass filter process and the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation. The ratio Δδa / ΔGya for calculating the correction amount of the stability factor Kh provided to the initial value Kh0 is calculated.

Therefore, compared with the case where the ratio Δδbpf / ΔGyftbpf for calculating the correction amount is obtained based on the lateral acceleration Gyftbpf of the vehicle after the bandpass filter processing and the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation, the lateral acceleration of the vehicle is obtained. It is possible to reduce the possibility that the stability factor Kh is estimated inaccurately due to the instantaneous fluctuation of the front wheel steering angle deviation converted value Δδbpf of Gyftbpf or yaw rate deviation.

Further, according to the above-described embodiments, the integrated value Δδa is an integrated value of the front wheel steering angle deviation converted value Δδ of the yaw rate deviation in which the deviation between the transient yaw rate γtr and the actual yaw rate γ is replaced with the deviation of the steering angle of the front wheels. . Therefore, the stability factor Kh can be estimated without being affected by the vehicle speed V. Therefore, the stability factor Kh can be accurately estimated as compared with the case where the integrated value of the yaw rate deviation index value is, for example, the integrated value of the deviation between the transient yaw rate γtr and the actual yaw rate γ. Further, it avoids the complexity of estimating the stability factor Kh for each vehicle speed V and changing the stability factor Kh used for the calculation of the target yaw rate γtt according to the vehicle speed V. Can be reduced.

Further, according to each of the above-described embodiments, whether or not it is necessary to adjust the integrated value Δδa of the front wheel rudder angle deviation converted value Δδbpf and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle in step 210. A determination is made. When a positive determination is made, an adjustment gain Gaj of 1 or less is calculated at step 220. In step 230, the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation after being adjusted by the adjustment gain Gaj and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are calculated.

Therefore, for example, when the loading state of the vehicle largely changes, the stability factor Kh when the previous integrated values Δδa and ΔGya are adjusted and the current stability factor Kh estimated in step 250 of the previous cycle are calculated. In a situation where the magnitude of the deviation ΔKh is increased, the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle are estimated as the stability factor Kh. It is possible to reliably prevent adverse effects.

Further, according to each of the above-described embodiments, in step 220, the adjustment gain Gaj is calculated according to the equation 21 based on the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle. Is done. Accordingly, the adjustment gain Gaj can be variably set according to the magnitude of the integrated value Δδa of the front wheel steering angle deviation converted value Δδbpf of the yaw rate deviation and the integrated value ΔGya of the lateral acceleration Gyftbpf of the vehicle. Therefore, the possibility that the estimation error of the stability factor may increase due to the adjustment gain Gaj being too large can be reduced as compared with the case where the adjustment gain Gaj is constant. It is possible to reduce the possibility that the S / N ratio for estimating the stability factor is lowered due to being too small.

Further, according to each of the above-described embodiments, it is determined in step 280 whether or not the storage of the estimated value of the stability factor Kh is permitted, and when an affirmative determination is made, step 290 is performed. At this time, the estimated value of the stability factor Kh is stored in the EEPROM. Therefore, the estimated value of the stability factor Kh can be stored in the EEPROM when the estimated value of the stability factor Kh substantially matches the actual stability factor. In other words, until the estimated value of the stability factor Kh substantially matches the actual stability factor, the estimation of the stability factor Kh is repeated without storing the estimated value of the stability factor Kh unnecessarily in the EEPROM. Thus, the estimated value of the stability factor Kh can be gradually brought closer to the actual stability factor.

Further, according to each of the above-described embodiments, it is determined in step 200 whether or not the vehicle is in a turning traveling state, and when an affirmative determination is made, step 210 and subsequent steps are executed. Therefore, in a situation where the vehicle is not in a turning state and the stability factor Kh cannot be accurately estimated, it is possible to prevent the step 210 and subsequent steps from being performed unnecessarily and the stability factor Kh from being estimated incorrectly. can do.
[First modification]

FIG. 8 is a flowchart showing a main part of the routine for estimating the stability factor Kh in the first modification example in which the first and second embodiments are partially modified. In FIG. 9, steps corresponding to the steps shown in FIG. 3 are assigned the same step numbers as those shown in FIG. The same applies to the flowchart of FIG.

In this first modification, when step 180 is completed, the number of reciprocating steering operations performed by the driver per unit time is calculated as the steering frequency fs in step 182. Further, the cut-off frequency fhc is calculated from the map corresponding to the graph shown in FIG. 9 based on the steering frequency fs so that the cut-off frequency fhc of the high-pass filter processing in step 190 becomes smaller as the steering frequency fs becomes lower. .

In the high-pass filter processing of the vehicle lateral acceleration Gyft and the front wheel rudder angle deviation converted value Δδ in step 190, the cutoff frequency is set to the cutoff frequency fhc calculated in step 82. The

In the first and second embodiments described above, the cut-off frequency fhc of the high-pass filter process in step 190 is constant. Therefore, when the cutoff frequency fhc is set to a high value so that the influence of the zero offset of the sensor is surely removed, the stability factor Kh is estimated in a situation where the number of reciprocating steering operations per unit time is small. There is a risk that you will not be able to. Conversely, if the cut-off frequency fhc is set to a low value, the influence of the zero offset of the sensor cannot be effectively removed in a situation where the number of reciprocating steerings by the driver per unit time is large. There is.

On the other hand, according to the first modified example, the cutoff frequency fhc is variably set according to the steering frequency fs so that the cutoff frequency fhc becomes smaller as the steering frequency fs becomes lower. Therefore, in the situation where the number of reciprocating steerings by the driver per unit time is large, the effect of the zero offset of the sensor is effectively removed, while in the situation where the number of reciprocating steerings by the driver per unit time is small. It is possible to prevent the ability factor Kh from being estimated.

The cut-off frequency fhc is calculated from the map based on the steering frequency fs, but may be calculated as a function of the steering frequency fs.
[Second modification]

FIG. 10 is a flowchart showing the main part of the routine for estimating the stability factor Kh in the second modification example in which the first and second embodiments are partially modified.

In the second modified example, when step 180 is completed, the number of reciprocating steering operations by the driver per unit time is calculated as the steering frequency fs in step 184. Further, the lower the steering frequency fs, the lower the cut-off frequency fhc of the high-pass filter process, and the higher the absolute value of the longitudinal acceleration Gx of the vehicle, the higher the cut-off frequency fhc of the high-pass filter process. Based on the absolute value of the longitudinal acceleration Gx, the cutoff frequency fhc is calculated from a map corresponding to the graph shown in FIG.

Then, in the high-pass filter processing of the vehicle lateral acceleration Gyft and the front wheel rudder angle deviation converted value Δδ in step 190, the cutoff frequency is set to the cutoff frequency fhc calculated in step 184. The

The error of the steering angle δ of the front wheels caused by the zero point offset of the steering angle sensor 34 is δ0, and the error of the vehicle lateral acceleration Gy caused by the zero point offset of the lateral acceleration sensor 40 is Gy0. An error in the yaw rate γ of the vehicle due to the zero point offset of the yaw rate sensor 36 is assumed to be γ0. Considering these errors, the deviation Δδt of the steering angle of the front wheels is expressed by the above equation 17.

Therefore, the influence of the zero point offset of the sensor is the second to fourth terms of the above equation 17, that is, δ0−KhdeGy0L−γ0L / V. Therefore, the greater the change in the vehicle speed V, that is, the magnitude of the longitudinal acceleration Gx of the vehicle, the greater the influence of the zero offset of the sensor on the change in the steady-state standard yaw rate γt, and conversely the smaller the magnitude of the longitudinal acceleration Gx of the vehicle. Therefore, the influence of the zero offset of the sensor on the change in the steady-state standard yaw rate γt is reduced.

According to the second modification, the cutoff frequency fhc is also based on the absolute value of the longitudinal acceleration Gx of the vehicle so that the higher the absolute value of the longitudinal acceleration Gx of the vehicle is, the higher the cutoff frequency fhc of the high-pass filter processing is. Variable setting. Therefore, it is possible to obtain the same operational effects as those of the first modification described above, and to effectively eliminate the influence of the zero offset of the sensor regardless of the change in the vehicle speed V.

The cut-off frequency fhc is calculated from the map based on the steering frequency fs and the absolute value of the longitudinal acceleration Gx of the vehicle, but is calculated as a function of the absolute value of the steering frequency fs and the longitudinal acceleration Gx of the vehicle. Also good.
[Third modification]

FIG. 12 is a flowchart showing the main part of the routine for estimating the stability factor Kh in the third modified example in which the first and second embodiments are partially modified.

In this third modification, if it is determined in step 200 that the vehicle is in a turning state, step 205 is executed prior to step 210. In step 205, it is determined whether or not the vehicle is in a state where the stability factor Kh can be estimated with high reliability. If a negative determination is made, the control returns to step 20 and an affirmative determination is made. If so, control proceeds to step 210.

In this case, when the following (B1) and (B2) are established, it may be determined that the vehicle is in a situation where the stability factor Kh can be estimated with high reliability.
(B1) The traveling road is not a bad road.
(B2) Not braking.

The condition of B1 takes into consideration that noise is superimposed on the actual yaw rate γ on rough roads and that the grip state of the tire with respect to the road surface tends to fluctuate. The condition of B2 is based on the fact that the calculation of the steady standard yaw rate γt according to the above equation 11 is premised on that there is no influence of the braking force.

Therefore, according to the third modified example, the first and second embodiments or the first and second embodiments in which it is not determined whether or not the vehicle is in a state where the stability factor Kh can be estimated with high reliability. The stability factor Kh can be estimated with higher accuracy than in the second modification example.

Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

For example, in each of the above-described embodiments and modifications, the means for acquiring the lateral acceleration Gy information of the vehicle is the lateral acceleration sensor 40, but the lateral acceleration sensor itself forms part of the vehicle travel control device. The means for acquiring the vehicle lateral acceleration information may be the electronic control device 30 itself that acquires the lateral acceleration Gy information by communication from the travel control device.

The lateral acceleration Gy of the vehicle is a value detected by the lateral acceleration sensor 40, but the product of the yaw rate γ detected by the yaw rate sensor 36 and the vehicle speed V detected by the vehicle speed sensor 42 is substituted for the lateral acceleration Gy of the vehicle. May be.

In the second embodiment described above, the estimated longitudinal acceleration Gxh of the vehicle is calculated based on the master cylinder pressure Pm or the accelerator opening Acc, and based on the deviation between the estimated longitudinal acceleration Gxh and the longitudinal acceleration Gx of the vehicle. Thus, the weight W of the vehicle is estimated. However, the vehicle weight W may be estimated by an arbitrary method. For example, in the case of a vehicle including a load sensor or a vehicle height sensor in the suspension, the vehicle weight W may be estimated based on the detection results.

In each of the above-described embodiments and modifications, the front wheel rudder angle deviation converted value of the yaw rate deviation obtained by replacing the deviation between the transient yaw rate γtr and the actual yaw rate γ with the deviation of the rudder angle of the front wheels in step 180. Is calculated. However, the deviation between the transient yaw rate γtr and the actual yaw rate γ is subjected to the high-pass filter processing, whereby the yaw rate deviation Δγbpf after the band-pass filter processing is calculated. The ratio of the integrated value Δγa of the yaw rate deviation Δγbpf to ΔGya may be calculated, and the estimated value of the stability factor Kh may be calculated according to the following equation 29 based on the integrated value ratio Δγbpf / ΔGya.
Kh = Kh0 + (Δγbpf / ΔGya) / V (29)

Further, when the estimated value of the stability factor Kh is calculated according to the equation 29, it is preferable that a plurality of vehicle speed ranges are set and the estimated value of the stability factor Kh is calculated for each vehicle speed range. It is also preferable that the degree of convergence of the estimated value of the stability factor Kh is also calculated for each vehicle speed range, whereby the dead zone of the vehicle motion control is variably set for each vehicle speed range. Furthermore, it is preferable that the stability factor Kh used for calculating the target yaw rate in the vehicle motion control is also set to a value estimated for each vehicle speed range.

In each of the above-described embodiments and modifications, the adjustment gain Gaj is within the range of 1 or less, and the first adjustment gain (Δδamin / | current Δδa |) and the second adjustment gain (ΔGyamin / | The larger one of the current ΔGya |) is set. However, one of the first and second adjustment gains may be omitted, and the other of the first and second adjustment gains may be corrected to be the adjustment gain Gaj.

Claims (8)

1. The relationship between various loading states, vehicle stability factors, and vehicle lateral acceleration is obtained in advance as a reference relationship and stored in the storage means to obtain vehicle lateral acceleration information. An estimated value of the stability factor of the vehicle based on the relationship between the calculated estimated value of the stability factor and the lateral acceleration of the vehicle at the same time as the traveling data of the vehicle used for the calculation of the estimated value, and A vehicle loading state estimation method, wherein the vehicle loading state is estimated based on the reference relationship.
2. The relationship between various loading states, vehicle stability factors and vehicle lateral acceleration for a plurality of vehicle weight categories is obtained in advance as a reference relationship and stored in the storage means to obtain vehicle lateral acceleration information and turn Calculates the vehicle stability data based on the vehicle running data at the time, obtains vehicle weight information, and determines the vehicle weight category and reference relationship based on the vehicle weight. The vehicle loading state is estimated based on the relationship between the estimated stability factor value, the vehicle travel data provided for the calculation of the estimated value, the lateral acceleration of the vehicle at the same time, and the determined reference relationship. A vehicle loading state estimation method characterized by:
3. The vehicle loading state estimation method according to claim 1 or 2, characterized in that it is estimated which of the various loading states.
4. The lateral acceleration of the vehicle from which the component below the first predetermined frequency is removed using the index value of the deviation between the transient yaw rate of the vehicle and the actual yaw rate of the vehicle, which is in a first order lag relationship with the standard yaw rate of the vehicle, as the yaw rate deviation index value 4. The vehicle stability factor is estimated based on a relationship between the yaw rate deviation index value from which a component having a frequency equal to or lower than the second predetermined frequency has been removed. 5. Vehicle loading state estimation method.
5. Storage means for storing, as a reference relationship, relationships among various loading states, vehicle stability factors, and vehicle lateral accelerations obtained in advance; means for acquiring vehicle lateral acceleration information; Stability factor estimating means for calculating an estimated value of the stability factor of the vehicle based on the travel data, and the stability factor estimated value calculated by the stability factor estimating means and the calculation of the estimated value. A vehicle loading state estimation device that estimates a loading state of a vehicle on the basis of a relationship between the vehicle traveling data and the lateral acceleration of the vehicle at the same time and the reference relationship.
6. Storage means for storing, as a reference relationship, various loading states obtained in advance for a plurality of vehicle weight categories, vehicle stability factors, and vehicle lateral acceleration, and means for acquiring vehicle lateral acceleration information And a stability factor estimating means for calculating an estimated value of the stability factor of the vehicle based on the running data of the vehicle at the time of turning, and a means for acquiring information on the weight of the vehicle, and based on the weight of the vehicle The relationship between the vehicle weight category and the standard is determined, and the estimated value of the stability factor calculated by the stability factor estimating means and the side of the vehicle at the same time as the running data of the vehicle used for the calculation of the estimated value are determined. A vehicle loading state estimation device that estimates a loading state of a vehicle based on a relationship with acceleration and a relationship between the determined reference.
7. The vehicle loading state estimation device according to claim 5 or 6, wherein the loading state estimation device estimates which one of the various loading states.
8. The stability factor estimating means uses a yaw rate deviation index value as an index value of a deviation between a vehicle transient yaw rate and a vehicle actual yaw rate that is in a first-order lag relationship with a standard yaw rate of the vehicle, and a component that is equal to or lower than a first predetermined frequency. 8. The vehicle stability factor is estimated based on a relationship between a lateral acceleration of the vehicle from which the noise is removed and a yaw rate deviation index value from which a component equal to or lower than the second predetermined frequency is removed. The vehicle loading state estimation device according to any one of the above.

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